The present invention relates to a gate valve used on, e.g., a load lock chamber or a process chamber in a semiconductor processing system for subjecting a target substrate, such as a semiconductor wafer, to a process. The term xe2x80x9csemiconductor processxe2x80x9d used herein includes various kinds of processes which are performed to manufacture a semiconductor device or a structure having wiring layers, electrodes, and the like to be connected to a semiconductor device, on a target substrate, such as a semiconductor wafer or an LCD substrate, by forming semiconductor layers, insulating layers, and conductive layers in predetermined patterns on the target substrate.
Conventionally, a structure utilizing a link mechanism or a cam mechanism is known as a driving mechanism for a gate valve. For example, Jpn. Pat. Appln. KOKAI Publication No. 5-196450 discloses a gate valve employing a link mechanism, as shown in FIG. 10. Jpn. Pat. Appln. KOKAI Publication No. 10-159999 discloses a gate valve employing a cam mechanism, as shown in FIGS. 11A and 11B.
The gate valve 100 shown in FIG. 10 is disposed between a load lock chamber 110 and a process chamber 120. The gate valve 100 includes a base body 102 and a valve plug 105 disposed in a gate casing 106. The base body 102 is connected to an actuator 101. A guide rail 107 is disposed on the wall of the gate casing 106 on the load lock chamber 110 side, so that the base body 102 is guided to move up and down. The valve plug 105 is connected to the base body 102 by links 103 and 104 at upper and lower positions. The valve plug 105 is further connected to the base body 102 by a spring 108. The valve plug 105 opens and closes an opening portion 121 of a process chamber 120.
When the opening portion 121 of the process chamber 120 is closed, the actuator 101 is activated to integratedly move up the base body 102 and the valve plug 105 along the guide rail 107. Even after a roller 109 disposed at the top of the valve plug 105 comes into contact with the ceiling of the gate casing 106, the base body 102 keeps moving up. Consequently, the valve plug 105 cannot move up any more, but moves toward the opening portion 121 of the process chamber 120 against the action of the spring 108 while rotating the roller 109. When the base body 102 reaches the upper end, the height of the base body 102 is leveled with that of the valve plug 105. At this time, the valve plug 105 is strongly pushed against the opening portion 121 of the process chamber 120 by the links 103 and 104, so that the opening portion 121 is closed.
When the opening portion 121 is opened, the actuator 101 is activated in the opposite direction to move down the base body 102. Consequently, the valve plug 105 is pulled by the spring 108 toward the base body 102, so that the opening portion 121 is opened. Then, the base body 102 moves down further, and the valve plug 105 returns to the initial state by the action of the spring 108.
The gate valve 100 shown in FIG. 10, i.e., disclosed in Jpn. Pat. Appln. KOKAI Publication No. 5-196450, employs members, such as the guide rail 107 and the spring 108, other than the link mechanism, at positions near the valve plug 105, to realize a sliding movement of the base body 102 and the valve plug 105, and their movement to/from the opening portion. As a result, this structure entails a problem in that the roller 109 comes into contact with the inner wall of the gate casing 106, thereby most likely generating particles.
On the other hand, the gate valve 200 shown in FIGS. 11A and 11B includes a valve plug 201 for opening and closing an opening portion 210. A pair of right and left side plates 202 are fixed to the valve plug 201 at each of the upper and lower levels. Each of the side plates 202 is provide with a first guide groove 203 formed therein and having a unique shape.
The gate valve 200 also includes valve plug driving rods 205, which are provided with second guide grooves 204 formed therein and each having a unique shape corresponding to the first guide groove 203. The valve plug driving rods 205 are connected to the valve plug 201 by shaft rollers 206 each inserted in the first and second guide grooves 203 and 204. The valve driving rods 205 are further connected to the side plates 202 by springs 207.
FIG. 11B is an enlarged view showing the relationship between the first and second guide grooves 203 and 204, and the roller 206. As shown in FIG. 11B, when the opening portion 210 is in an open state, the guide grooves 203 and 204 are displaced from each other, viewed from a lateral side.
When the opening portion 210 is closed, the valve plug driving rods 205 are activated to move down the valve plug 201 with a gap interposed between the valve plug 201 and the valve seat 211. The valve plug 201 comes into contact with a stopper 212 below the opening portion 210, but the valve plug driving rods 205 move down further against the action of the springs 207. Consequently, the rollers 206 slightly shift the side plates 202 through the first guide grooves 203 toward the opening portion 210, and finally push the valve plug 201 against the valve seat 211.
When the opening portion 210 is opened, the valve plug driving rods 205 move up. At this time, the rollers 206 move up in the respective first guide grooves 203 by the springs 207 to separate the valve plug 201 from the valve seat 212. Then, the valve plug driving rods 205 further move up, so that the valve plug 201 moves up with the gap kept between the valve plug 201 and the opening portion 210 to return the initial state, while the rollers 206 maintain the state shown in FIG. 11B.
The gate valve 200 shown FIGS. 11A and 11B, i.e., disclosed in Jpn. Pat. Appln. KOKAI Publication No. 10-159999, employs the first and second guide grooves 203 and 204 to realize the up/down movement of the valve plug 201, and its movement to/from the opening portion. As a result, this structure requires the guide grooves to be worked with high accuracy, and also entails a problem in that particles are easily generated near the valve plug 201 and the opening portion 210.
An object of the present invention is to provide a gate valve for a semiconductor processing system, which hardly generates particles near a valve seat (opening portion) and a valve plug.
According to a first aspect of the present invention, there is provided a gate valve for a semiconductor processing system, comprising:
a base frame configured movable in a first direction to move toward and away from a valve seat, which surrounds an opening portion and has a first seal surface facing a first reference plane;
a first stopper configured to define a movement limit of the base frame on the valve seat side;
a swing frame attached to the base frame, and configured rotatable on a second reference plane perpendicular to the first reference plane;
a valve plug attached to the swing frame, and having a second seal surface to engage with the first seal surface thereby to close the opening portion;
a link mechanism connecting the swing frame to the base frame, and configured to bend and stretch while flexing an intermediate portion;
a driving mechanism connected to the intermediate portion, and configured to move the intermediate portion in the first direction; and
a biasing member configured to apply a resistant force against rotation of the swing frame relative to the base frame,
wherein, it is preset that, when the opening portion is closed, the intermediate portion is moved by the driving mechanism toward the valve seat to first cause the base frame to move until the base frame comes into contact with the first stopper, and then cause the link mechanism to bend or stretch thereby to rotate the swing frame, such that the valve plug seats itself on the valve seat, and the first and second seal surfaces engage with each other.
In a second aspect, there is provided an apparatus according to the first aspect, further comprising a guide fixed relative to the valve seat, wherein the base frame moves along the guide.
In a third aspect, there is provided an apparatus according to the first aspect, further comprising a damper disposed between the base frame and the swing frame to absorb an impact caused when the swing frame rotates relative to the base frame by an action of the biasing member.
In a fourth aspect, there is provided an apparatus according to the first aspect, wherein the driving mechanism comprises a reciprocation rod connected to the intermediate portion.
In a fifth aspect, there is provided an apparatus according to the fourth aspect, wherein the reciprocation rod penetrates a slit hole formed in the intermediate portion, and the reciprocation rod is movable relative to the intermediate portion in a range allowed by the slit hole.
In a sixth aspect, there is provided an apparatus according to the fourth aspect, wherein the reciprocation rod is connected to the intermediate portion by a position adjusting mechanism, such that a connecting position of the reciprocation rod relative to the intermediate portion is adjustable by the position adjusting mechanism.
In a seventh aspect, there is provided an apparatus according to the fourth aspect, wherein one end limit of a stroke of the reciprocation rod is set to correspond to a bend-and-stretch state of the link mechanism formed when the valve plug seats itself on the valve seat.
In an eighth aspect, there is provided an apparatus according to the first aspect, further comprising a second stopper configured to define a movement limit of the intermediate portion on the valve seat side to correspond to a bend-and-stretch state of the link mechanism formed when the valve plug seats itself on the valve seat.
In a ninth aspect, there is provided an apparatus according to the eighth aspect, wherein the second stopper is fixed to the base frame.
In a tenth aspect, there is provided an apparatus according to the first aspect, wherein the biasing member connects the swing frame to the base frame.
In an eleventh aspect, there is provided an apparatus according to the first aspect, wherein the link mechanism comprises first and second levers connected to the base frame and the swing frame, respectively, to be pivotable on the second reference plane, and the intermediate portion connects the first and second levers to be pivotalbe to each other on the second reference plane.
In a twelfth aspect, there is provided an apparatus according to the first aspect, wherein the first direction is substantially parallel to the first reference plane.
In a thirteenth aspect, there is provided an apparatus according to the first aspect, wherein the valve plug and the link mechanism are connected to the swing frame at first and second positions, respectively, sandwiching a position at which the swing frame is attached to the base frame.
In a fourteenth aspect, there is provided an apparatus according to the first aspect, wherein the opening portion is formed in a sidewall of an airtight chamber, in which a target substrate is accommodated, and the opening portion is formed to allow the target substrate to pass therethrough.
In a fifteenth aspect, there is provided an apparatus according to the fourteenth aspect, wherein the valve seat and the valve plug are arranged to isolate a vacuum atmosphere inside the airtight chamber from an atmospheric environment outside the airtight chamber.
According to a sixteenth aspect of the present invention, there is provided a gate valve for a semiconductor processing system, comprising:
a base frame configured movable in a first direction to move toward and away from a valve seat, which surrounds an opening portion and has a first seal surface facing a first reference plane;
a first stopper configured to define a movement limit of the base frame on the valve seat side;
a swing frame attached to the base frame, and configured rotatable on a second reference plane perpendicular to the first reference plane;
a valve plug attached to the swing frame, and having a second seal surface to engage with the first seal surface thereby to close the opening portion;
a link mechanism connecting the swing frame to the base frame, and configured to bend and stretch while flexing an intermediate portion, the link mechanism comprising first and second levers connected to the base frame and the swing frame, respectively, to be pivotable on the second reference plane, the intermediate portion connecting the first and second levers to be pivotalbe to each other on the second reference plane;
a driving mechanism comprising a reciprocation rod connected to the intermediate portion, and configured to move the intermediate portion in the first direction; and
a biasing member connecting the swing frame to the base frame, and configured to apply a resistant force against rotation of the swing frame relative to the base frame,
wherein, it is preset that, when the opening portion is closed, the intermediate portion is moved by the driving mechanism toward the valve seat to first cause the base frame to move until the base frame comes into contact with the first stopper, and then cause the link mechanism to bend or stretch thereby to rotate the swing frame, such that the valve plug seats itself on the valve seat, and the first and second seal surfaces engage with each other.